Stable aqueous solution-type oxidizing agent composition for explosives

ABSTRACT

An aqueous solution-type oxidizing agent composition consisting of an aqueous solution containing an oxidizing agent, which consists of ammonium nitrate as a main component and an inorganic chlorate, and further containing a water-soluble phosphate as a stabilizer, which is stable, inhibits the decomposition of ammonium nitrate, and has high storage stability.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a stable aqueous solution-typeoxidizing agent composition consisting of an aqueous solution containingan oxidizing agent, which consists of ammonium nitrate as a maincomponent and an inorganic chlorate, and further containing a phosphateas a stabilizer.

(b) Description of the Prior Art

It has hitherto been known that inorganic chlorate decomposes at hightemperature and further its aqueous solution decomposes in the acidicregion when in the presence of chlorine ions.

However, there has not been fully investigated the behavior at hightemperature of an aqueous solution of an oxidizing agent consisting ofammonium nitrate as a main component and inorganic chlorate.

U.S. Pat. No. 3,282,753 specification discloses the use of sodiumcarbonate, sodium hydroxide or potassium hydroxide as a stabilizer forimproving the storage stability at high temperature of a slurryexplosive containing a solution of the above described oxidizing agent.

However, although the decomposition of inorganic chlorate in anexplosive can be somewhat suppressed by these stabilizers, ammoniumnitrate decomposes gradually to decrease its inherent action as anoxidizing agent. Moreover, in this slurry explosive, inorganic chlorate,ammonium nitrate and the like are dispersed in water to form a watergel, and therefore ammonium nitrate decomposes rapidly. Further, theinorganic chlorate and ammonium nitrate are present in a crystallineform, and therefore the inorganic chlorate decomposes rapidly. While, ina homogeneous aqueous solution of oxidizing agent, wherein ammoniumnitrate and inorganic chlorate are completely dissolved in water, evenwhen the above described stabilizer is used, it is difficult to preventthe decomposition of the inorganic chlorate, particularly itsdecomposition at high temperature, and further it is difficult tosuppress the decomposition of ammonium nitrate.

The inventors have found that, when an aqueous solution of an oxidizingagent consisting of ammonium nitrate as a main component and aninorganic chlorate is formed into a very small droplet, that is, formedinto a water-in-oil emulsion, the crystallization of the oxidizingagents of inorganic chlorate and ammonium nitrate can be suppressed andthe decomposition of the oxidizing agents can be prevented, and havealready filed a water-in-oil emulsion explosive composition, wherein thecrystallization of the oxidizing agents is suppressed and thedecomposition thereof is prevented (Japanese Patent Application No.2,771/81).

However, although the above described water-in-oil emulsion explosivecomposition is stable after the explosive composition has been formed,the aqueous solution of the oxidizing agents used for the production ofthe explosive composition must be kept at high temperature during itsstorage in order to prevent the crystallization of the oxidizing agents,resulting in the decomposition of the inorganic chlorate. Therefore, thestability, particularly stability at high temperature, of the aqueoussolution of the oxidizing agent is still insufficient.

The inventors have made various investigations with respect to thestabilization of an aqueous solution of an oxidizing agent whichconsists of ammonium nitrate as a main component and an inorganicchlorate, and found out that, when a specifically limited stabilizer isadded to the solution, the decomposition of ammonium nitrate does notoccur, and the decomposition of the inorganic chlorate is suppressedeven at high temperature, and further the stabilizer-containing aqueoussolution of the oxidizing agent is sufficiently stable even in thepresence of chloride ions, to accomplish the objects of the presentinvention.

SUMMARY OF THE INVENTION

The present invention provides a stable aqueous solution-type oxidizingagent composition consisting of an aqueous solution of an oxidizingagent, which consists of ammonium nitrate as a main component and aninorganic chlorate, said aqueous solution containing a water-solubleinorganic phosphate.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The aqueous solution of an oxidizing agent to be used in the presentinvention is an aqueous solution always containing ammonium nitrate as amain component and an inorganic chlorate. As the inorganic chlorate, useis made of alkali metal salts or alkaline earth metal salts of inorganicchloric acid, and for example, sodium chlorate, potassium chlorate,barium chlorate, strontium chlorate and the like. These chlorates can beused alone or in admixture. In addition to the inorganic chlorate andammonium nitrate, the aqueous solution of oxidizing agent mayoccasionally contain nitrates, such as sodium nitrate, calcium nitrateand the like; perchlorates, such as ammonium perchlorate, sodiumperchlorate and the like; chlorides, such as sodium chloride and thelike; and water-soluble organic substances, such as polyhydric alcoholof mannitol and the like.

The specifically limited stabilizer, which can be used in the presentinvention, is a water-soluble phosphate, and includes, for example, thefollowing phosphates:

Orthophosphate represented by the general formula M₃ PO₄, wherein Mrepresents sodium, potassium, magnesium and the like; polyphosphaterepresented by the general formula M_(n+2) P_(n) O_(3n+1), wherein nrepresents an integer of 2, 3, 4 . . . (n=2: pyrophosphate, n=3:tripolyphosphate, and n=4: tetrapolyphosphate), and M represents sodium,potassium, magnesium and the like; metaphosphate represented by thegeneral formula (MPO₃)_(n), wherein n represents an integer of 3 or 4(n=3: trimethaphosphate, and n=4: tetrametaphosphate) and M representssodium, potassium, magnesium, etc.; and the like. In the above describedphosphates, a part of sodium, potassium and magnesium represented by Mmay be substituted by hydrogen.

The above described phosphates are used alone or in admixture.

The amount of each of the above described components can be properlydetermined depending upon the concentration of ammonium nitrate, the pHof the aqueous solution, the amount of the other substances to be mixed,the strength as an alkali of the water-soluble phosphate, and the like.It is generally preferable that the amount of ammonium nitrate is58-89.99% by weight (hereinafter, % means % by weight), that ofinorganic chlorate is 2-20%, that of water is 8-20%, and that ofwater-soluble phosphate is 0.01-2%. When the amount of water-solublephosphate is less than 0.01%, the phosphate cannot exhibit the action asa stabilizer for the aqueous solution of oxidizing agent; while when theamount exceeds 2%, the relative amount of oxidizing agent is small, andhence the action of the oxidizing agent is decreased, and further theaction of the stabilizer for the aqueous solution of oxidizing agent isnot so improved as compared with the case where the amount of thephosphate is 2%, and the use of more than 2% of the water-solublephosphate is expensive and is not preferable.

The stable aqueous solution-type oxidizing agent composition of thepresent invention can be produced, for example, in the following manner.

A given amount of ammonium nitrate and a given amount of water-solublephosphate are dissolved in a given amount of water at a temperature of50°-120° C. to form a solution, and a given amount of inorganic chlorateis dissolved in the solution under stirring.

When it is ocassionally intended to add other inorganic oxidizing acidsalt, chloride, water-soluble organic substance and the like to thestable aqueous solution-type oxidizing agent composition of the presentinvention, these compounds or substances are added to the aqueoussolution of ammonium nitrate and water-soluble phosphate before theinorganic chlorate is added to the solution.

The stable aqueous solution-type oxidizing agent composition obtained bythe above described method is free from the decomposition of ammoniumnitrate, and substantially free from the decomposition of inorganicchlorate even at high temperature, and is sufficiently stable even inthe presence of chloride ions. Therefore, the stable aqueoussolution-type oxidizing agent composition is most suitable to be used asan oxidizer for explosives.

The following examples are given for the purpose of illustration of thisinvention, and are not intended as limitations thereof. In the examples,"parts" and "%" are indicated by weight basis.

EXAMPLE 1

A stable aqueous solution-type oxidizing agent composition having acompounding recipe shown in the following Table 1 was produced in thefollowing manner.

To 95 parts (9.50%) of water were added 856.8 parts (85.68%) of ammoniumnitrate and 0.2 part (0.02%) of disodium hydrogenphosphate, and theresulting mixture was heated to 100° C. to dissolve the nitrate andphosphate in the water. Then, 48 parts (4.80%) of sodium chlorate wereadded to the solution and dissolved therein to form a stable aqueoussolution-type oxidizing agent composition.

The resulting aqueous solution of the oxidizing agent composition wascharged into a flask of 500 ml capacity equipped with a cooling tube inorder to prevent the evaporation of water, and the flask was placed inan oil bath kept at 100° C. to effect the storage stability test of theaqueous solution.

In the storage stability test, a part of the aqueous solution of theoxidizing agent composition was taken out from the flask at certain timeintervals, and the amount of chlorate ion was analyzed by the method ofthe instant invention. Further, the decomposition rate of the sodiumchlorate was determined from the difference between the amount ofchlorate ion in the original solution and the amount of chlorate ion inthe sample solution.

The decomposition of ammonium nitrate was judged by the presence orabsence of ammonium smell.

The chlorate ion was analyzed as follows. Proper amounts of sodiumnitrite and an aqueous solution of silver nitrate were added to a samplesolution. After the solution was made into nitric acid-acidic, thesolution was heated to convert the chlorate ion into chloride ion, andto precipitate the resulting silver chloride. After the precipitate ofsilver chloride was filtered off, iron (II) ion was added to thefiltrate as an indicator, the excess amount of silver nitrate remainingin the filtrate was determined by titrating the amount of filtrate withan aqueous solution of ammonium thiocyanate, and the amount of thechlorate ion was calculated from the reacted amount of silver nitrate.

The above obtained decomposition rate of the chlorate is shown inTable 1. The storage stability test was effected up to 10 days. Evenafter 10 days, an ammonia smell was not observed and it was ascertainedthat ammonium nitrated did not decompose.

EXAMPLES 2-5

Stable aqueous solution-type oxidizing agent compositions having acompounding recipe shown in Table 1, wherein the kind and mixing ratioof water-soluble phosphate were changed from those in Example 1, wereproduced in the same manner as described in Example 1.

The resulting oxidizing agent compositions were subjected to the samestorage stability test as described in Example 1. The obtained resultsare shown in Table 1. It was ascertained that the chlorate and ammoniumnitrate did not decompose at all in all the oxidizing agentcompositions.

EXAMPLE 6

A stable aqueous solution-type oxidizing agent composition was producedin the same manner as described in Example 1, except that potassiumpyrophosphate was used as the water-soluble phosphate in addition todisodium hydrogenphosphate.

The resulting composition was subjected to the same storage stabilitytest as described in Example 1, and it was ascertained that sodiumchlorate and ammonium nitrate did not decompose at all. The obtainedresults are shown in Table 1.

EXAMPLE 7

A stable aqueous solution-type oxidizing agent composition was producedin the same manner as described in Example 1, except that sodiumchloride was added to the reaction system.

The resulting composition was subjected to the same storage stabilitytest as described in Example 1, and it was ascertained that ammoniumnitrate did not decompose at all. The obtained results are shown inTable 1.

EXAMPLE 8

A stable aqueous solution-type oxidizing agent composition having acompounding recipe shown in Table 1, wherein a polyhydric alcohol ofmannitol was added to the compounding recipe of Example 1, was producedin the same manner as described in Example 1.

The resulting composition was subjected to the same storage stabilitytest as described in Example 1, and it was ascertained that sodiumchlorate and ammonium nitrate did not decompose at all. The obtainedresults are shown in Table 1.

                                      TABLE 1                                     __________________________________________________________________________     Example No.          1   2   3   4   5  6   7  8                             __________________________________________________________________________    Compounding                                                                          Ammonium nitrate                                                                             85.68                                                                             85.60                                                                             74.60                                                                             65.80                                                                             60.20                                                                            86.00                                                                             60.20                                                                            69.20                         recipe (%)                                                                           Sodium nitrate --  --  4.10                                                                              --  -- --  -- --                                   Calcium nitrate                                                                              --  --  --  22.20                                                                             -- --  -- --                                   Sodium chlorate                                                                              4.80                                                                              4.80                                                                              --  --  19.40                                                                            4.60                                                                              18.40                                                                            15.30                                Potassium chlorate                                                                           --  --  9.90                                                                              --  -- --  -- --                                   Barium chlorate                                                                              --  --  --  2.40                                                                              -- --  -- --                                   Water          9.50                                                                              9.50                                                                              10.90                                                                             8.60                                                                              18.70                                                                            9.30                                                                              18.40                                                                            10.70                                Sodium chloride                                                                              --  --  --  --  -- --   1.30                                                                            --                                   Mannitol       --  --  --  --  -- --  --  3.80                                Disodium hydrogenphosphate                                                                   0.02                                                                              --  --  --  -- 0.05                                                                              --  1.00                                Magnesium hydrogenphosphate                                                                  --  0.10                                                                              --  --  -- --  -- --                                   Potassium pyrophosphate                                                                      --  --  0.50                                                                              --  -- 0.05                                                                              -- --                                   Sodium tripolyphosphate                                                                      --  --  --  1.00                                                                              -- --  -- --                                   Sodium metaphosphate                                                                         --  --  --  --   1.70                                                                            --   1.70                                                                            --                            Storage                                                                              Decomposition                                                                          1 day 0   0   0   0   0  0   0  0                             stability                                                                            percentage of                                                                          3 days                                                                              0   0   0   0   0  0   0.1                                                                              0                                    chlorate at                                                                             5 days                                                                             0.1 0   0   0   0  0   0.1                                                                              0                                    100° C. (%)                                                                     10 days                                                                             0.2 0   0   0   0  0   0.2                                                                              0                                    Ammonia smell (10 days)                                                                      none                                                                              none                                                                              none                                                                              none                                                                              none                                                                             none                                                                              none                                                                             none                          __________________________________________________________________________

COMPARATIVE EXAMPLES 1-4

Aqueous solution-type oxidizing agent compositions having a compoundingrecipe shown in the following Table 2, wherein disodiumhydrogenphosphate used in Example 1 was not used, were produced in thesame manner as described in Example 1.

The resulting compositions were subjected to the same storage stabilitytest as described in Example 1. The obtained results are shown in Table2.

COMPARATIVE EXAMPLE 5

An aqueous solution-type oxidizing agent composition having acompounding recipe shown in Table 2, wherein sodium metaphosphate usedin Example 7 was not used, was produced in the same manner as describedin Example 7.

The resulting composition was subjected to the same storage stabilitytest as described in Example 1. The obtained results are shown in Table2.

COMPARATIVE EXAMPLES 6 AND 7

Aqueous solution-type oxidizing agent compositions having a compoundingrecipe shown in Table 2, wherein sodium carbonate or sodium hydroxidewas used in place of disodium hydrogenphosphate used in Example 1respectively, were produced in the same manner as described in Example1.

Immediately after the production of this composition, the, ammonia smellwas violent. It was ascertained that ammonium nitrate had decomposed.

The resulting compositions were subjected to the same storage stabilitytest as described in Example 1. The obtained results are shown in Table2.

COMPARATIVE EXAMPLE 8

An aqueous solution-type oxidizing agent composition was produced in thesame manner as described in Example 7, except that sodium carbonate wasused in place of sodium metaphosphate. Immediately after the production,of this composition the, ammonia smell was violent. It was ascertainedthat ammonium nitrate had decomposed.

The resulting composition was subjected to the same storage stabilitytest as described in Example 1. The obtained results are shown in Table2.

                                      TABLE 2                                     __________________________________________________________________________     Comparative example No.                                                                       1  2  3  4  5  6   7   8                                     __________________________________________________________________________    Compounding                                                                          Ammonium nitrate                                                                        85.70                                                                            75.10                                                                            65.80                                                                            61.90                                                                            61.90                                                                            84.90                                                                             85.68                                                                             60.20                                 recipe (%)                                                                           Sodium nitrate                                                                          --  4.10                                                                            -- -- -- --  --  --                                           Calcium nitrate                                                                         -- -- 23.20                                                                            -- -- --  --  --                                           Sodium chlorate                                                                          4.80                                                                            -- -- 19.40                                                                            19.40                                                                             4.70                                                                              4.80                                                                             18.40                                        Potassium chlorate                                                                      --  9.90                                                                            -- -- -- --  --  --                                           Barium chlorate                                                                         -- --  2.40                                                                            -- -- --  --  --                                           Water      9.50                                                                            10.90                                                                             8.60                                                                            18.70                                                                            18.70                                                                             9.40                                                                              9.50                                                                             18.40                                        Sodium chloride                                                                         -- -- -- --  1.30                                                                            --  --   1.30                                        Sodium carbonate                                                                        -- -- -- -- --  1.00                                                                             --   1.70                                        Sodium hydroxide                                                                        -- -- -- -- -- --   0.02                                                                             --                                    Storage                                                                              Decomp-                                                                              1 day                                                                            2.4                                                                              2.6                                                                              0.2                                                                              0.2                                                                               1.5                                                                             0   0.1 0.1                                   stability                                                                            osition                                                                              3 days                                                                           100                                                                              100                                                                              6.6                                                                              5.5                                                                              100                                                                              0.2 0.6 0.4                                          percentage                                                                           5 days                                                                           -- -- 100                                                                              100                                                                              -- 0.5 2.2 2.0                                          of    10 days                                                                           -- -- -- -- -- 5.4 11.0                                                                              10.8                                         chlorate at                                                                   100° C. (%)                                                            Ammonia smell                                                                           none                                                                             none                                                                             none                                                                             none                                                                             none                                                                             strong*                                                                           strong*                                                                           strong*                                      (10 days)                                                              __________________________________________________________________________     *Violent ammonia smell even just after the production                    

The results of the above described Examples and Comparative exampleswill be explained in detail. In the aqueous solution-type oxidizingagent compositions containing no water-soluble phosphate (Comparativeexamples 1-4), although ammonium nitrate does not decompose up to 10days in a storage stability test under a condition of 100° C., theinorganic chlorate decomposes completely after only 3 to 5 days. On thecontrary, in the stable aqueous solution-type oxidizing agentcompositions containing a water-soluble phosphate according to thepresent invention (Examples 1-6 and 8), ammonium nitrate does notdecompose at all, and further the inorganic chlorate does not decomposeat all or decomposes in a very small amount (0.2% after 10 days) underthe same condition as described above.

In the aqueous solution-type oxidizing agent compositions using acommonly known alkali substance as a stabilizer (Comparative examples 6and 7), the ammonia smell is violent just after the production, andfurther the ammonia smell is strong throughout the storage stabilitytest. That is, it is clear that ammonium nitrate has decomposed.Moreover, the decomposition percentage of the inorganic chlorate is verylarge and is about 5-10% after 10 days.

In the aqueous solution-type oxidizing agent composition containingchloride ion (Comparative example 5), although the decomposition ofammonium nitrate does not occur during the storage stability test, theinorganic chlorate has completely decomposed only after 3 days. On thecontrary, in the stable aqueous solution-type oxidizing agentcomposition containing a water-soluble phosphate of the presentinvention (Example 7), the decomposition percentage of the inorganicchlorate is only 0.2% after 10 days. In the aqueous solution-typeoxidizing agent composition containing a commonly known stabilizer(Comparative example 8), the decomposition percentage of the inorganicchlorate is as large as 10.8% after 10 days, and further thedecomposition of ammonium nitrate is observed.

As described above, in the stable aqueous solution-type oxidizing agentcomposition according to the present invention, ammonium nitrate doesnot decompose, and further the decomposition of inorganic chlorate doesnot occur at all or is very small even at high temperature, and moreoverthe composition is satisfactorily stable even in the presence ofchloride ions.

We claim:
 1. A stable aqueous solution-type oxidizing agent compositionconsisting of an aqueous solution of an oxidizing agent, which consistsof 58-89.99% by weight of ammonium nitrate as a main component and 2-20%by weight of an inorganic chlorate, 8-20% by weight of water and 0.01-2%by weight of a water-soluble inorganic phosphate.
 2. The stable aqueoussolution-type oxidizing agent composition according to claim 1, whereinsaid water-soluble inorganic phosphate comprises one of the groupconsisting essentially of phosphate formed from orthophosphoric acid,poly-phosphoric acid, or metaphosphoric acid.
 3. The stable aqueoussolution-type oxidizing agent composition according to claim 2, whereinsaid inorganic chlorate is a chlorate of alkali metal or alkaline earthmetal.
 4. The stable aqueous solution-type oxidizing agent compositionaccording to claim 2, wherein said phosphate is a phosphate of alkalimetal or alkaline earth metal.